The present invention relates generally to a method for analyzing electrical power systems, and more particularly to a method for managing, transferring and visualizing synchrophasor measurement data related to power system events.
Generally, electrical power originates at a generation station and is transmitted to a load by a system of conductors and other equipment that make up an electrical power system. The equipment that makes up an electric power system can include generators, transmission lines, busbars, switches, reclosers, insulators, capacitors, and the like. Over time, or as the result of some particular incidents, the generators, transmission lines, or other equipment can cease to operate normally or fail. Sometimes a failure results in an abnormally high current that can further damage the power system, injure end users, or damage end user devices and equipment or cause large scale cascading power system outages. Failures also sometimes result in degraded power quality or loss of electric service.
In an effort to identify failures or conditions that may lead to failure, utilities may monitor the operation of an electrical power system by evaluating one or more signals indicative of power system properties such as voltage magnitudes, voltage phase angles, currents, phase angle differences between two buses, etc. One such method is using synchrophasor measurements for real-time security monitoring and post event analysis.
A “phasor” is a complex number representation of magnitude and phase angle in AC electrical signals. Phasors can be measured using commercially available phasor measurement units (“PMUs”) located at or near the substations or generation stations of an interconnected electric power system being monitored. Typically, multiple PMUs will be installed at geographically spread-apart locations within an electrical power system. The PMUs may be synchronized by global positioning system (“GPS”) clock signal so that simultaneous measurements may be taken by a group of PMUs, which are then transferred to a phasor data center. These are referred to as “synchrophasors”.
Once synchrophasor data is collected it may be transferred to a user's computer equipped with a software visualization application that creates a graphical representation of the data, and evaluated by a power system operator or operational planning engineers or reliability coordinator for improving their situational awareness of interconnected power systems. Typically, synchrophasor measurements are taken at a scan rate of 30 samples per second. A power system event or a sequence of power system events, such as large generator outages or transmission line outages, generate a large volume of synchrophasor measurements related to the events in a specified time period (typically one minute to several minutes).
Prior art power system visualization applications using PMU data are mainly based on client-server technology in which each power system event is stored and transferred within the system as a data object. They lack high fidelity event replay with dynamic voltage or frequency contour calculations 30 times per second and cannot support a large number of simultaneous users. Furthermore, using existing visualization technology, it can take a long time (for example 30 to 50 minutes) for a user to be able to start the event replay for a current event or for a selected previous event and therefore it was not possible to perform near real-time event replay for monitoring and analyzing the on-going events.